DNS and logonserver

I am trying to learn more about DNS and the _msdcs and things below it.  I just learned that these are records that are queried by other machines to find out where a service is located at.   What I am working on now is trying to figure out what makes a client choose one logon server or another.   I have a DC1 and DC2 which are both global catalog AD servers Then I have a Monitor machine which is AD server only.  the DC1 contains the DNS.   When my exchange server or even my machine logs on its logon server ends up being the monitor machine.   What causes that and how do I get it to logon to DC1?

thanks in advance for any help offered.
Who is Participating?
PakaConnect With a Mentor Commented:
There probably two mechanisms running here.  One is the logonserver environmental variable and the other is the DNS query for domain controllers.  If memory serves, the client will use the last setting for logonserver instead of querying for a DNS server if it is set.  If that fails, the logon service will query DNS for an authenticating domain controller.

Try setting the logon server to DC1 using "set logonserver=DC1" at the command prompt and the netlogon service should attempt to authenticate with DC1 then next time it starts.
windows looks after itself using KCC and other technologies - a kind of auto load balancing, with windows 2000+ the only way you can force a logon to a certain server that i am aware of, is to have sites setup in AD sites and Services and assign subnets to them, otherwise,  if you are in a single site, there is no need to do anything
techbnjcompAuthor Commented:
I have two sites and actually a few more servers that I did not mention as they are in another site.    I see a priority and weight in the kerberous dns records and wondered if that was causing some kind of election.    
Free Tool: Path Explorer

An intuitive utility to help find the CSS path to UI elements on a webpage. These paths are used frequently in a variety of front-end development and QA automation tasks.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

have you configured your sites in AD?
you can use a login script to tell you what server its connecting to
techbnjcompAuthor Commented:
Guys thanks for your help but I am not being articulate enough here.   I do know what server they are using as logonserver (cmd line   set logonserver tells me).  I am trying to tell how the dns records determine whether it uses dc1, dc2, or monitor.   Is it priority or what is causing it to use monitor instead of dc1 ?
itcozaConnect With a Mentor Commented:
Hi techbnjcomp,

I think I understand what you are after.  Have a look at this MS KB:  http://support.microsoft.com/default.aspx?scid=kb;en-us;831201
It is apparent that the servers are given their priority for service in the DNS SVC records.  The article also describes the steps you need to take if you want to change this.

Normally, it uses DNS Round Robin to find a server in the same site.  If Round Robin is not checked in DNS then it will use the first server it finds that answers it.

You can use DNS weighting, but it's not recommended because everyone will use that DC rather than spread out the load.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

All Courses

From novice to tech pro — start learning today.